This application claims benefit of and priority to Federal Republic of Germany Priority Application 101 39 173.0, filed Aug. 16, 2001 including the specification, drawings, claims and abstract, which is incorporated herein by reference in its entirety.
The invention relates to an arrangement for rotatable adjustment of a cap on an eyepiece housing with a stationary pin pointing radially outward from the eyepiece housing and a groove which is assigned to the pin, arranged on the inner side of the cap and rises in the axial direction.
An arrangement of this type is known from U.S. Pat. No. 5,784,207 What is known as an eyepiece cup is arranged longitudinally displaceably on an eyepiece housing, in order for it to be possible for glasses-wearers and normal-sighted observers to set an optimum position of the eye in relation to the exit pupil of the eyepiece. A screw is attached to the eyepiece housing, the head of which is guided in a groove which is in the inner wall of the eyepiece cup. By rotating the eyepiece cup, the height of the eyepiece cup is adjusted relative to the eyepiece housing. Provided opposite the groove-guide in the cross section of the arrangement, between the eyepiece cup and the eyepiece housing, is a catch arrangement for different extension positions of the eyepiece cup. The catch arrangement consists of a plate spring element which is provided with a nose and is arranged on the eyepiece housing, the nose engaging in appropriately shaped notches in the inner wall of the eyepiece cup.
The large number of parts makes assembly more difficult and is expensive. The resilience of the catching element wears out as a result of material fatigue. Demounting of the eyepiece cup for cleaning purposes is not envisaged.
An eyepiece housing with an adjustable, in particular asymmetrically shaped eyepiece cup is known from DE 299 04 366 U1. A guide, which likewise consists of a groove and a pin, is intended to ensure that the eyepiece cup is stopped in the displacement end positions concerned and always has the same orientation in the circumferential direction. To this end, catching positions are provided, which are arranged on a line parallel to the longitudinal axis of the eyepiece housing. As the guide groove is inclined in relation to the longitudinal axis, its direction always has to be diverted, in relation to the designated line parallel to the longitudinal axis, for passage into the catching position. The catching is brought about by an angular change in direction of the guide groove.
While it is true that this guide manages without additional moving parts, it nevertheless requires a relatively complex shape of the guide tracks, which can wear at the angular diversions to the catch position when used for a relatively long time. Demounting of the eyepiece cup is not envisaged in this case either.
It is therefore an object of the invention to provide a simple and cost-effective fastening, guidance and catching arrangement for an eyepiece cup to be adjusted rotatably on an eyepiece housing, which manages with only one moving mechanical component which is non-sensitive to environmental influences and, for cleaning, can be removed from the eyepiece housing, cleaned and replaced rapidly and without additional tools.
According to the invention, this object is achieved in an arrangement of the type referred to in the introduction by virtue of the characterizing features of the invention.
In one embodiment of the invention, there is an arrangement for rotatable adjustment of a cap on an eyepiece housing with a stationary pin pointing radially outward from the eyepiece housing and a groove which is assigned to the pin, arranged on the inner side of the cap and rises in the axial direction, wherein, in a plane at right angles to the longitudinal axis (4) of the eyepiece housing (10), three pins (11) are arranged on the latter, the heads of which pins have at least approximately the same spacing from the longitudinal axis (4), and wherein the sliding bottom (7) of the groove (3) assigned to each pin (11) has a smaller spacing in relation thereto, so that the cap (1) bears against the pins (11) under prestress.
In another embodiment of the invention, there is an arrangement for rotatable adjustment of a cap on an eyepiece housing wherein the grooves (3) have catching recesses (8, 8xe2x80x2, 8xe2x80x3) in their sliding bottom (7), the shape of which recesses is adapted to the heads of the pins (11) and the depth of which recesses is selected in such a way that, in the catching positions, the cap (1) bears against the pins (11) under a prestress which is reduced in relation to the position on the sliding bottom (7).
In another embodiment of the invention, there is an arrangement for rotatable adjustment of a cap on an eyepiece housing wherein the undersize of the sliding bottom (7) in relation to the head of the pin (11) is 1.0% to 2.0%, and the corresponding undersize of the catching recesses (8, 8xe2x80x2, 8xe2x80x3) is 0.01% to 0.9% of the spacing of the head from the longitudinal axis (4).
In another embodiment of the invention, there is an arrangement for rotatable adjustment of a cap on an eyepiece housing wherein the grooves (3) are, in their part (6) located next to the lower edge (5) of the cap (1), angled in the opposite direction to the axial incline, and are open at the lower edge (5) of the cap (1).
In another embodiment of the invention, there is an arrangement for rotatable adjustment of a cap on an eyepiece housing wherein the delimitation (9) of the grooves (3) running out at an acute angle in relation to the lower edge (5) of the cap (1) is milled off parallel to the longitudinal axis (4).
In another embodiment of the invention, there is an arrangement for rotatable adjustment of a cap on an eyepiece housing wherein the grooves (3) have a catching recess (8) in the corner of the angle.
In another embodiment of the invention, there is an arrangement for rotatable adjustment of a cap on an eyepiece housing wherein the heads of the pins (11) are spherically shaped.
In another embodiment of the invention, there is an arrangement for rotatable adjustment of a cap on an eyepiece housing wherein the heads of the pins (11) are spherically polished.
In another embodiment of the invention, there is an arrangement for rotatable adjustment of a cap on an eyepiece housing wherein the cap (1) comprises an abrasion-resistant, elastically deformable plastic with a low coefficient of thermal expansion.
In another embodiment of the invention, there is an arrangement for rotatable adjustment of a cap on an eyepiece housing wherein the cap (1) comprises a glass-fiber-reinforced polycarbonate.
In another embodiment of the invention, there is an arrangement for rotatable adjustment of a cap on an eyepiece housing wherein the cap (1) is provided with a removable cover (2) made of an elastomeric material.